Questions tagged [endocrinology]

The area of physiology dealing with the production and effects of hormones.

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Can ovulation and menstruation occur simultaneously?

Is that possible that ovulation happens in the time of actual menstrual haemorrhage in human females - let say in a case that woman has 21 day cycle and her menstrual period is 7 days? If yes, does ...
Ilan's user avatar
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Apparent paradox in Glucagon action

Glucagon stimulates glycogenolysis and gluconeogenesis, thus increasing the plasma glucose concentration — so that tissues get enough glucose in the fasting state. However glucagon also inhibits ...
ANA negative's user avatar
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Why are fearful stimuli more powerful at night?

For example, horror movies appear to be scarier when viewed at night than during broad day light. Does light have any role in this phenomenon? Are there changes in hormones at night versus during ...
Mesentery's user avatar
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What causes humans to be sleepy?

Is there a hormone or group of hormones that regulates when we feel sleepy late at night, or in the morning? Or is sleepiness caused by some other non-hormonal mechanism? (e.g. pure psychological, ...
Kenshin's user avatar
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21 votes
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Why does the face turn pale in dangerous situations?

I know what the effects are of a dangerous situation on the brain, i.e., an activation of the hypothalamic-pituitary-adrenal (HPA) axis which eventually results in an increased heart rate and elevated ...
Probably's user avatar
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Can parts of a human brain be asleep independently of each other, or vary in the times required for them to fall asleep?

I know that some birds and marine animals can continue complicated activity (swimming, flying?) while one hemisphere of their brain is asleep. I'm interested if human brain has some parts of it that ...
Alex Stone's user avatar
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What is the female equivalent of the morning erection that some men experience?

There was question about what causes "morning wood." It was answered that the erection in the morning is caused by decline of norepinephrine during REM sleep. Which in part allows to prevent ...
jnovacho's user avatar
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Do men have significant hormonal cycles?

I know there's a similar question here. But that discussion dissolved into lunar cycle and a correlation with it. I want to find more towards the original question of is there a periodic hormone ...
Software Mechanic's user avatar
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Which brain regions are D1 dopamine receptors expressed, and which brain regions are D2 dopamine receptors expressed?

This is a follow-up question to If D1 receptors stimulate adenylate cyclase (through GPCRs) and D2 receptors inhibit it, then why do mutations in both have similar effects?. As a further question - I'...
InquilineKea's user avatar
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If so many different hormones/molecules work by activating adenylyl cyclase, how do they have different effects?

It seems that many hormones and molecules work by activating adenylyl cyclase to convert $\text{ATP}$ to $\text{cAMP}$, such as adrenaline and glucagon. Both of these seem to bind to $\text G$ protein ...
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Can androgen-insensitive genetic-males get pregnant?

According to the linked report, people with androgen insensitivity syndrome appear as male, but have both feminine and masculine outer genitalia. However, I was not able to find out whether their ...
Shadow Wizard Love Zelda's user avatar
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Is there such thing as a generic "metabolic type"?

A while ago I picked up a book called "Eat right for your metabolic type". The book discussed the effects of the endocrine system on the overall shape and the speed of metabolism. The book outlined ...
Alex Stone's user avatar
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Can we artificially increase human growth using HGH?

Robert Pershing Wadlow was a man who lived in the first half of the twentieth century. He had hyperplasia of his pituitary gland, which caused him over-produce human growth hormone (HGH), and as a ...
Cat's user avatar
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What is the physiological difference between cortisone and cortisol?

There is only hydrogen bond different. Cortisol is synthesized by our body, while cortisone is given to the patient. Why you cannot give cortisol directly to the patient? I think the reason is ...
Léo Léopold Hertz 준영's user avatar
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3 answers
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Abnormal Prolactin Level [closed]

I want to know what makes the balance of the Prolactin abnormal. Is that related to the presence of a nodule near the pituitary?
Hanieh's user avatar
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How quickly do estrogens break down in the environment?

Of all the synthetic hormones we use, estrogens are probably the most common. They are used for birth control as well as hormone replacement therapy. This researcher also shows that there is plenty ...
shigeta's user avatar
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What light intensity determines the start/end of a photoperiod in humans?

I'm reading this article, which discusses the influence of Long Photoperiod (LP) and Short Photoperiod (SP) on melatonin production: HIOMT drives the photoperiodic changes in the amplitude of the ...
Alex Stone's user avatar
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How are melatonin levels measured in humans?

I'm wondering how it is possible to measure diurnal variations of melatonin levels in humans. I keep reading that there should be a large difference in amplitude between melatonin levels measured at ...
Alex Stone's user avatar
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3 votes
2 answers
973 views

What is the difference between neurotransmitters acting as neurotransmitters and hormones?

My main confusion is what differentiates the action of a transmitter substance as a neurotransmitter and as a hormone. For example, when norepinephrine is being talked about as transmitter substance ...
EMMs2008's user avatar
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Euthyrodism and goitre

I read in Tortora and Derrickson that goitre is associated with euthyrodism. How is that possible?
biogirl's user avatar
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What controls the size of breasts?

I am not a biology student, just a curious person. To be specific, I'm talking about female humans. I know that it might apply to other mammals. What controls the size of breasts? I have heard about ...
Santosh Kumar's user avatar
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Pituitary giants - is the fusing of growth plates dependent on amount of growth hormone in blood?

I wanted to ask a couple questions related to pituitary giants (people who are giants because of some anomaly, such as a tumor, in their pituitary gland). Some of these giants seem to keep growing ...
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